Code review comment for lp:~widelands-dev/widelands/net-boost-asio

Pushed a fix for an assert(state_ == OFFLINE) bug which I encountered. The problem was that on crash of a hosted game the logic jumped back to the main menu without closing the connection to the metaserver. So when the player tries to connect again, he already is connected to the metaserver (and not offline).

To reproduce the bug:
- Login to the metaserver
- Cut your wifi cable
- Try to host a game. Should fail and jump you back into the main menu
- Try to connect to the metaserver again (I did this one without network)
- Game crashes due to the assert